Vehicle-to-everything (V2X) communication transmit parameter selection using joint communication-radar side information

ABSTRACT

A method of wireless communication by a first user equipment (UE) includes receiving a vehicle-to-everything (V2X) message from a second UE. The method also includes periodically transmitting and receiving a radar signal to sense an environment of the first UE. The method includes estimating joint communication and radar side information based on the V2X message and the radar signal. The method further includes predicting a communication state between the first UE and the second UE based on the joint communication and radar side information. The method still further includes updating communication transmit parameters based on the communication state.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications, andmore specifically to vehicle-to-everything (V2X) communication transmitparameter selection using joint communication-radar side information.

BACKGROUND

Wireless communications systems are widely deployed to provide varioustelecommunications services such as telephony, video, data, messaging,and broadcasts. Typical wireless communications systems may employmultiple-access technologies capable of supporting communications withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunications standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunications standardis fifth generation (5G) new radio (NR). 5G NR is part of a continuousmobile broadband evolution promulgated by Third Generation PartnershipProject (3GPP) to meet new requirements associated with latency,reliability, security, scalability (e.g., with Internet of Things(IoT)), and other requirements. 5G NR includes services associated withenhanced mobile broadband (eMBB), massive machine type communications(mMTC), and ultra-reliable low latency communications (URLLC). Someaspects of 5G NR may be based on the fourth generation (4G) long termevolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunications standards thatemploy these technologies.

Wireless communications systems may include or provide support forvarious types of communications systems, such as vehicle relatedcellular communications systems (e.g., cellular vehicle-to-everything(CV2X) communications systems). Vehicle related communications systemsmay be used by vehicles to increase safety and to help preventcollisions of vehicles. Information regarding inclement weather, nearbyaccidents, road conditions, and/or other information may be conveyed toa driver via the vehicle related communications system. In some cases,sidelink user equipment (UEs), such as vehicles, may communicatedirectly with each other using device-to-device (D2D) communicationsover a D2D wireless link. These communications can be referred to assidelink communications.

As the demands for sidelink communications increase in general, and CV2Xtechnology specifically penetrates the market and the number of carssupporting CV2X communication grows rapidly, the CV2X network isexpected to become increasingly crowded, especially for peak trafficscenarios. As a result, the chance of colliding allocations between UEsmay increase. An allocation collision may prevent successful decoding ofat least one of the colliding UE transmissions and in some cases mayprevent all of the colliding UE transmissions from being decoded. Forsafety reasons, there is a need to minimize the duration of repetitivecollisions between semi-persistently scheduled allocations of collidinguser equipment (UEs) or to minimize the number of future collisions ingeneral.

SUMMARY

In aspects of the present disclosure, a method of wireless communicationby a first user equipment (UE) includes receiving avehicle-to-everything (V2X) message from a second UE. The method alsoincludes periodically transmitting and receiving a radar signal to sensean environment of the first UE. The method also includes estimatingjoint communication and radar side information based on the V2X messageand the radar signal. The method further includes predicting acommunication state between the first UE and the second UE based on thejoint communication and radar side information. The method still furtherincludes updating communication transmit parameters based on thecommunication state.

Other aspects of the present disclosure are directed to an apparatus forwireless communication by a first user equipment (UE) having a memoryand one or more processors coupled to the memory. The processor(s) isconfigured to receive a vehicle-to-everything (V2X) message from asecond UE. The processor(s) is also configured to periodically transmitand receive a radar signal to sense an environment of the first UE. Theprocessor(s) is also configured to estimate joint communication andradar side information based on the V2X message and the radar signal.The processor(s) is further configured to predict a communication statebetween the first UE and the second UE based on the joint communicationand radar side information. The processor(s) is still further configuredto update communication transmit parameters based on the communicationstate.

Other aspects of the present disclosure are directed to an apparatus forwireless communication by a first user equipment (UE) including meansfor receiving a vehicle-to-everything (V2X) message from a second UE.The apparatus also includes means for periodically transmitting andreceiving a radar signal to sense an environment of the first UE. Theapparatus also includes means for estimating joint communication andradar side information based on the V2X message and the radar signal.The apparatus further includes means for predicting a communicationstate between the first UE and the second UE based on the jointcommunication and radar side information. The apparatus still furtherincludes means for updating communication transmit parameters based onthe communication state.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communications device, and processing system assubstantially described with reference to and as illustrated by theaccompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described. The conception and specificexamples disclosed may be readily utilized as a basis for modifying ordesigning other structures for carrying out the same purposes of thepresent disclosure. Such equivalent constructions do not depart from thescope of the appended claims. Characteristics of the concepts disclosed,both their organization and method of operation, together withassociated advantages will be better understood from the followingdescription when considered in connection with the accompanying figures.Each of the figures is provided for the purposes of illustration anddescription, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a firstfifth generation (5G) new radio (NR) frame, downlink (DL) channelswithin a 5G NR subframe, a second 5G NR frame, and uplink (UL) channelswithin a 5G NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 is a diagram illustrating an example of a vehicle-to-everything(V2X) system, in accordance with various aspects of the presentdisclosure.

FIG. 5 is a block diagram illustrating an example of avehicle-to-everything (V2X) system with a road side unit (RSU),according to aspects of the present disclosure.

FIG. 6 is a graph illustrating a sidelink (SL) communications scheme, inaccordance with various aspects of the present disclosure.

FIG. 7 is a block diagram illustrating vehicle-to-everything (V2X)communication, in accordance with various aspects of the presentdisclosure.

FIG. 8 is a block diagram illustrating radar sensing, in accordance withvarious aspects of the present disclosure.

FIG. 9 is a block diagram illustrating V2X communication, in accordancewith various aspects of the present disclosure.

FIG. 10 is a call flow diagram illustrating communication transmitparameter selection, in accordance with various aspects of the presentdisclosure.

FIG. 11 is a flow diagram illustrating an example process performed, forexample, by a user equipment, in accordance with various aspects of thepresent disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully below withreference to the accompanying drawings. This disclosure may, however, beembodied in many different forms and should not be construed as limitedto any specific structure or function presented throughout thisdisclosure. Rather, these aspects are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of thedisclosure to those skilled in the art. Based on the teachings, oneskilled in the art should appreciate that the scope of the disclosure isintended to cover any aspect of the disclosure disclosed, whetherimplemented independently of or combined with any other aspect of thedisclosure. For example, an apparatus may be implemented or a method maybe practiced using any number of the aspects set forth. In addition, thescope of the disclosure is intended to cover such an apparatus ormethod, which is practiced using other structure, functionality, orstructure and functionality in addition to or other than the variousaspects of the disclosure set forth. It should be understood that anyaspect of the disclosure disclosed may be embodied by one or moreelements of a claim.

Several aspects of telecommunications systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, and/or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described using terminologycommonly associated with 5G and later wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunications systems, such as and including 3G and/or 4G technologies.

In cellular communications networks, wireless devices may generallycommunicate with each other via one or more network entities such as abase station or scheduling entity. Some networks may supportdevice-to-device (D2D) communications that enable discovery of, andcommunications with nearby devices using a direct link between devices(e.g., without passing through a base station, relay, or another node).D2D communications can enable mesh networks and device-to-network relayfunctionality. Some examples of D2D technology include Bluetoothpairing, Wi-Fi Direct, Miracast, and LTE-D. D2D communications may alsobe referred to as point-to-point (P2P) or sidelink communications.

D2D communications may be implemented using licensed or unlicensedbands. Additionally, D2D communications can avoid the overhead involvingthe routing to and from the base station. Therefore, D2D communicationscan improve throughput, reduce latency, and/or increase energyefficiency.

A type of D2D communications may include vehicle-to-everything (V2X)communications. V2X communications may assist autonomous vehicles incommunicating with each other. For example, autonomous vehicles mayinclude multiple sensors (e.g., light detection and ranging (LiDAR),radar, cameras, etc.). In most cases, the autonomous vehicle's sensorsare line of sight sensors. In contrast, V2X communications may allowautonomous vehicles to communicate with each other for non-line of sightsituations.

Sidelink (SL) communications refers to the communications among userequipment (UE) without tunneling through a base station (BS) and/or acore network. Sidelink communications can be communicated over aphysical sidelink control channel (PSCCH) and a physical sidelink sharedchannel (PSSCH). The PSCCH and PSSCH are similar to a physical downlinkcontrol channel (PDCCH) and a physical downlink shared channel (PDSCH)in downlink (DL) communications between a BS and a UE. For instance, thePSCCH may carry sidelink control information (SCI) and the PSCCH maycarry sidelink data (e.g., user data). Each PSCCH is associated with acorresponding PSSCH, where SCI in a PSCCH may carry reservation and/orscheduling information for sidelink data transmission in the associatedPSSCH. Use cases for sidelink communications may include, among others,vehicle-to-everything (V2X), industrial internet of things (IIoT),and/or NR-lite.

Conventionally, when a first user (e.g., user-A) transmits messages to asecond user (e.g., user-B) for high-data rate vehicular applications,user-A may experience reduced communication capability. For example,intermittent outages may be experienced. The reduced communicationcapability may be due to vehicular mobility and/or blockage of thecommunication path between vehicles. In order to enable robust andefficient communication, user-A performs additional training forbeamforming and communication channel sensing, which creates additionaloverhead and decreases the communication data rate.

According to aspects of the present disclosure, user-A may communicatein a robust, efficient manner with a high-data rate with user-B'svehicular applications, while reducing the need for additional trainingoverhead. User-A may adaptively select transmit parameters using jointcommunication-radar (JCR) side information. Additionally, user-A mayobtain the JCR side information by associating and correlating its radarside information with (vehicle-to-everything) V2X messages received fromuser-B. The V2X messages received from user-B may include personalsafety messages (PSMs) and basic safety messages (BSMs) to potentiallyenhance safety as well as traffic efficiency. User-A and user-B can bevehicles or vulnerable road users (VRUs). Pedestrians, bicyclists, androad construction crew are examples of VRUs. Devices at user-A anduser-B may include cell phones, vehicle/bike mounted hardware, andconstruction equipment, for example.

Using radar as a coarse estimate for selecting suitable communicationtransmit parameters may lead to a reduction in communication trainingoverhead, where the communication training may be directed to findingthe best beam and waveform parameters. After the coarse estimate isreceived from radar, communication can further optimize the bestbeamforming shape and gain if needed. Therefore, the communication datarate may improve and outages may be reduced.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an evolved packet core (EPC) 160, and anothercore network 190 (e.g., a 5G core (5GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells102′ (low power cellular base station). The macrocells include basestations. The small cells 102′ include femtocells, picocells, andmicrocells.

The base stations 102 configured for 4G LTE (collectively referred to asevolved universal mobile telecommunications system (UMTS) terrestrialradio access network (E-UTRAN)) may interface with the EPC 160 throughbackhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as next generation RAN(NG-RAN)) may interface with core network 190 through backhaul links184. In addition to other functions, the base stations 102 may performone or more of the following functions: transfer of user data, radiochannel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over backhaul links 134 (e.g., X2interface). The backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communications coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include home evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communications links 120 between the base stations 102 andthe UEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communications links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationslinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc., MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communications link 158. The D2D communications link 158 may usethe DL/UL WWAN spectrum. The D2D communications link 158 may use one ormore sidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communications may be through a variety of wireless D2Dcommunications systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunications links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include an eNB, gNodeB (gNB), or another typeof base station. Some base stations, such as gNB 180 may operate in atraditional sub 6 GHz spectrum, in millimeter wave (mmWave) frequencies,and/or near mmWave frequencies in communication with the UE 104. Whenthe gNB 180 operates in mmWave or near mmWave frequencies, the gNB 180may be referred to as an mmWave base station. Extremely high frequency(EHF) is part of the radio frequency (RF) in the electromagneticspectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between1 millimeter and 10 millimeters. Radio waves in the band may be referredto as a millimeter wave. Near mmWave may extend down to a frequency of 3GHz with a wavelength of 100 millimeters. The super high frequency (SHF)band extends between 3 GHz and 30 GHz, also referred to as centimeterwave. Communications using the mmWave/near mmWave radio frequency band(e.g., 3 GHz-300 GHz) has extremely high path loss and a short range.The mmWave base station 180 may utilize beamforming 182 with the UE 104to compensate for the extremely high path loss and short range.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a mobility management entity (MME) 162, otherMMEs 164, a serving gateway 166, a multimedia broadcast multicastservice (MBMS) gateway 168, a broadcast multicast service center (BM-SC)170, and a packet data network (PDN) gateway 172. The MME 162 may be incommunication with a home subscriber server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the serving gateway 166, which itself is connected to the PDNgateway 172. The PDN gateway 172 provides UE IP address allocation aswell as other functions. The PDN gateway 172 and the BM-SC 170 areconnected to the IP services 176. The IP services 176 may include theInternet, an intranet, an IP multimedia subsystem (IMS), a PS streamingservice, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS bearer services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSgateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a multicast broadcast single frequency network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include an access and mobility managementfunction (AMF) 192, other AMFs 193, a session management function (SMF)194, and a user plane function (UPF) 195. The AMF 192 may be incommunication with a unified data management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides quality of service(QoS) flow and session management. All user Internet protocol (IP)packets are transferred through the UPF 195. The UPF 195 provides UE IPaddress allocation as well as other functions. The UPF 195 is connectedto the IP services 197. The IP services 197 may include the Internet, anintranet, an IP multimedia subsystem (IMS), a PS streaming service,and/or other IP services.

The base station 102 may also be referred to as a gNB, Node B, evolvedNode B (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a transmit and receive point(TRP), or some other suitable terminology. The base station 102 providesan access point to the EPC 160 or core network 190 for a UE 104.Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, a tablet, a smart device, a wearable device, avehicle, an electric meter, a gas pump, a large or small kitchenappliance, a healthcare device, an implant, a sensor/actuator, adisplay, or any other similar functioning device. Some of the UEs 104may be referred to as IoT devices (e.g., a parking meter, gas pump,toaster, vehicles, heart monitor, etc.). The UE 104 may also be referredto as a station, a mobile station, a subscriber station, a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

Referring again to FIG. 1 , in certain aspects, a receiving device, suchas the UE 104, may adjust communication transmit parameters based onjoint communication-radar (JCR) side information. The UE 104 may includea JCR component 199 configured to receive a vehicle-to-everything (V2X)message from a second UE and periodically transmit and receive a radarsignal to sense an environment of the first UE. The JCR component 199 isalso configured to estimate joint communication and radar sideinformation based on the V2X message and the radar signal, predict acommunication state between the first UE and the second UE based on thejoint communication and radar side information, and update communicationtransmit parameters based on the communication state.

Although the following description may be focused on 5G NR, it may beapplicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, andother wireless technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplex (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplex (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and X isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

Other wireless communications technologies may have a different framestructure and/or different channels. A frame (10 ms) may be divided into10 equally sized subframes (1 ms). Each subframe may include one or moretime slots. Subframes may also include mini-slots, which may include 7,4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on theslot configuration. For slot configuration 0, each slot may include 14symbols, and for slot configuration 1, each slot may include 7 symbols.The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Thesymbols on UL may be CP-OFDM symbols (for high throughput scenarios) ordiscrete Fourier transform (DFT) spread OFDM (DFT-S-OFDM) symbols (alsoreferred to as single carrier frequency-division multiple access(SC-FDMA) symbols) (for power limited scenarios; limited to a singlestream transmission). The number of slots within a subframe is based onthe slot configuration and the numerology. For slot configuration 0,different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots,respectively, per subframe. For slot configuration 1, differentnumerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, persubframe. Accordingly, for slot configuration 0 and numerology μ, thereare 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing andsymbol length/duration are a function of the numerology. The subcarrierspacing may be equal to 2{circumflex over ( )}μp*15 kHz, where μ is thenumerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacingof 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz.The symbol length/duration is inversely related to the subcarrierspacing. FIGS. 2A-2D provide an example of slot configuration 0 with 14symbols per slot and numerology μ=0 with 1 slot per subframe. Thesubcarrier spacing is 15 kHz and symbol duration is approximately 66.7μs.

A resource grid may represent the frame structure. Each time slotincludes a resource block (RB) (also referred to as physical RBs (PRBs))that extends 12 consecutive subcarriers. The resource grid is dividedinto multiple resource elements (REs). The number of bits carried byeach RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as Rx for one particular configuration, where 100x is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A primary synchronization signal (PSS) may be within symbol2 of particular subframes of a frame. The PSS is used by a UE 104 todetermine subframe/symbol timing and a physical layer identity. Asecondary synchronization signal (SSS) may be within symbol 4 ofparticular subframes of a frame. The SSS is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DM-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSS and SSS to form a synchronization signal (SS)/PBCH block. TheMIB provides a number of RBs in the system bandwidth and a system framenumber (SFN). The physical downlink shared channel (PDSCH) carries userdata, broadcast system information not transmitted through the PBCH suchas system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. Although not shown, the UE may transmitsounding reference signals (SRS). The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARQ) acknowledgment/negative acknowledgment (ACK/NACK)feedback. The PUSCH carries data, and may additionally be used to carrya buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough automatic repeat request (ARQ), concatenation, segmentation, andreassembly of RLC service data units (SDUs), re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing ofMAC SDUs from TBs, scheduling information reporting, error correctionthrough HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an inverse fastFourier transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a fast Fourier transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with the JCR component 199 of FIG. 1 . In some aspects, theUE 104, 350 may include means for receiving, means for transmitting,means for estimating, means for predicting, means for updating, meansfor adjusting, and/or means for determining. Such means may include oneor more components of the UE 104, 350 described in connection with FIGS.1 and 3 .

FIG. 4 is a diagram of a device-to-device (D2D) communications system400, including V2X communications, in accordance with various aspects ofthe present disclosure. For example, the D2D communications system 400may include V2X communications, (e.g., a first UE 450 communicating witha second UE 451). In some aspects, the first UE 450 and/or the second UE451 may be configured to communicate in a licensed radio frequencyspectrum and/or a shared radio frequency spectrum. The shared radiofrequency spectrum may be unlicensed, and therefore multiple differenttechnologies may use the shared radio frequency spectrum forcommunications, including new radio (NR), LTE, LTE-Advanced, licensedassisted access (LAA), dedicated short range communications (DSRC),MuLTEFire, 4G, and the like. The foregoing list of technologies is to beregarded as illustrative, and is not meant to be exhaustive.

The D2D communications system 400 may use NR radio access technology. Ofcourse, other radio access technologies, such as LTE radio accesstechnology, may be used. In D2D communications (e.g., V2X communicationsor vehicle-to-vehicle (V2V) communications), the UEs 450, 451 may be onnetworks of different mobile network operators (MNOs). Each of thenetworks may operate in its own radio frequency spectrum. For example,the air interface to a first UE 450 (e.g., Uu interface) may be on oneor more frequency bands different from the air interface of the secondUE 451. The first UE 450 and the second UE 451 may communicate via asidelink component carrier, for example, via the PC5 interface. In someexamples, the MNOs may schedule sidelink communications between or amongthe UEs 450, 451 in licensed radio frequency spectrum and/or a sharedradio frequency spectrum (e.g., 5 GHz radio spectrum bands).

The shared radio frequency spectrum may be unlicensed, and thereforedifferent technologies may use the shared radio frequency spectrum forcommunications. In some aspects, a D2D communications (e.g., sidelinkcommunications) between or among UEs 450, 451 is not scheduled by MNOs.The D2D communications system 400 may further include a third UE 452.

The third UE 452 may operate on the first network 410 (e.g., of thefirst MNO) or another network, for example. The third UE 452 may be inD2D communications with the first UE 450 and/or second UE 451. The firstbase station 420 (e.g., gNB) may communicate with the third UE 452 via adownlink (DL) carrier 432 and/or an uplink (UL) carrier 442. The DLcommunications may be use various DL resources (e.g., the DL subframes(FIG. 2A) and/or the DL channels (FIG. 2B)). The UL communications maybe performed via the UL carrier 442 using various UL resources (e.g.,the UL subframes (FIG. 2C) and the UL channels (FIG. 2D)).

The first network 410 operates in a first frequency spectrum andincludes the first base station 420 (e.g., gNB) communicating at leastwith the first UE 450, for example, as described in FIGS. 1-3 . Thefirst base station 420 (e.g., gNB) may communicate with the first UE 450via a DL carrier 430 and/or an UL carrier 440. The DL communications maybe use various DL resources (e.g., the DL subframes (FIG. 2A) and/or theDL channels (FIG. 2B)). The UL communications may be performed via theUL carrier 440 using various UL resources (e.g., the UL subframes (FIG.2C) and the UL channels (FIG. 2D)).

In some aspects, the second UE 451 may be on a different network fromthe first UE 450. In some aspects, the second UE 451 may be on a secondnetwork 411 (e.g., of the second MNO). The second network 411 mayoperate in a second frequency spectrum (e.g., a second frequencyspectrum different from the first frequency spectrum) and may includethe second base station 421 (e.g., gNB) communicating with the second UE451, for example, as described in FIGS. 1-3 .

The second base station 421 may communicate with the second UE 451 via aDL carrier 431 and an UL carrier 441. The DL communications areperformed via the DL carrier 431 using various DL resources (e.g., theDL subframes (FIG. 2A) and/or the DL channels (FIG. 2B)). The ULcommunications are performed via the UL carrier 441 using various ULresources (e.g., the UL subframes (FIG. 2C) and/or the UL channels (FIG.2D)).

In conventional systems, the first base station 420 and/or the secondbase station 421 assign resources to the UEs for device-to-device (D2D)communications (e.g., V2X communications and/or V2V communications). Forexample, the resources may be a pool of UL resources, both orthogonal(e.g., one or more frequency division multiplexing (FDM) channels) andnon-orthogonal (e.g., code division multiplexing (CDM)/resource spreadmultiple access (RSMA) in each channel). The first base station 420and/or the second base station 421 may configure the resources via thePDCCH (e.g., faster approach) or RRC (e.g., slower approach).

In some systems, each UE 450, 451 autonomously selects resources for D2Dcommunications. For example, each UE 450, 451 may sense and analyzechannel occupation during the sensing window. The UEs 450, 451 may usethe sensing information to select resources from the sensing window. Asdiscussed, one UE 451 may assist another UE 450 in performing resourceselection. The UE 451 providing assistance may be referred to as thereceiver UE or partner UE, which may potentially notify the transmitterUE 450. The transmitter UE 450 may transmit information to the receivingUE 451 via sidelink communications.

The D2D communications (e.g., V2X communications and/or V2Vcommunications) may be carried out via one or more sidelink carriers470, 480. The one or more sidelink carriers 470, 480 may include one ormore channels, such as a physical sidelink broadcast channel (PSBCH), aphysical sidelink discovery channel (PSDCH), a physical sidelink sharedchannel (PSSCH), and a physical sidelink control channel (PSCCH), forexample.

In some examples, the sidelink carriers 470, 480 may operate using thePC5 interface. The first UE 450 may transmit to one or more (e.g.,multiple) devices, including to the second UE 451 via the first sidelinkcarrier 470. The second UE 451 may transmit to one or more (e.g.,multiple) devices, including to the first UE 450 via the second sidelinkcarrier 480.

In some aspects, the UL carrier 440 and the first sidelink carrier 470may be aggregated to increase bandwidth. In some aspects, the firstsidelink carrier 470 and/or the second sidelink carrier 480 may sharethe first frequency spectrum (with the first network 410) and/or sharethe second frequency spectrum (with the second network 411). In someaspects, the sidelink carriers 470, 480 may operate in anunlicensed/shared radio frequency spectrum.

In some aspects, sidelink communications on a sidelink carrier may occurbetween the first UE 450 and the second UE 451. In an aspect, the firstUE 450 may perform sidelink communications with one or more (e.g.,multiple) devices, including the second UE 451 via the first sidelinkcarrier 470. For example, the first UE 450 may transmit a broadcasttransmission via the first sidelink carrier 470 to the multiple devices(e.g., the second and third UEs 451, 452). The second UE 451 (e.g.,among other UEs) may receive such broadcast transmission. Additionallyor alternatively, the first UE 450 may transmit a multicast transmissionvia the first sidelink carrier 470 to the multiple devices (e.g., thesecond and third UEs 451, 452). The second UE 451 and/or the third UE452 (e.g., among other UEs) may receive such multicast transmission. Themulticast transmissions may be connectionless or connection-oriented. Amulticast transmission may also be referred to as a groupcasttransmission.

Furthermore, the first UE 450 may transmit a unicast transmission viathe first sidelink carrier 470 to a device, such as the second UE 451.The second UE 451 (e.g., among other UEs) may receive such unicasttransmission. Additionally or alternatively, the second UE 451 mayperform sidelink communications with one or more (e.g., multiple)devices, including the first UE 450 via the second sidelink carrier 480.For example, the second UE 451 may transmit a broadcast transmission viathe second sidelink carrier 480 to the multiple devices. The first UE450 (e.g., among other UEs) may receive such broadcast transmission.

In another example, the second UE 451 may transmit a multicasttransmission via the second sidelink carrier 480 to the multiple devices(e.g., the first and third UEs 450, 452). The first UE 450 and/or thethird UE 452 (e.g., among other UEs) may receive such multicasttransmission. Further, the second UE 451 may transmit a unicasttransmission via the second sidelink carrier 480 to a device, such asthe first UE 450. The first UE 450 (e.g., among other UEs) may receivesuch unicast transmission. The third UE 452 may communicate in a similarmanner.

In some aspects, for example, such sidelink communications on a sidelinkcarrier between the first UE 450 and the second UE 451 may occur withouthaving MNOs allocating resources (e.g., one or more portions of aresource block (RB), slot, frequency band, and/or channel associatedwith a sidelink carrier 470, 480) for such communications and/or withoutscheduling such communications. Sidelink communications may includetraffic communications (e.g., data communications, controlcommunications, paging communications and/or system informationcommunications). Further, sidelink communications may include sidelinkfeedback communications associated with traffic communications (e.g., atransmission of feedback information for previously-received trafficcommunications). Sidelink communications may employ at least onesidelink communications structure having at least one feedback symbol.The feedback symbol of the sidelink communications structure may allotfor any sidelink feedback information that may be communicated in thedevice-to-device (D2D) communications system 400 between devices (e.g.,a first UE 450, a second UE 451, and/or a third UE 452). As discussed, aUE may be a vehicle (e.g., UE 450, 451), a mobile device (e.g., 452), oranother type of device. In some cases, a UE may be a special UE, such asa road side unit (RSU).

FIG. 5 illustrates an example of a vehicle-to-everything (V2X) systemwith a roadside unit (RSU), according to aspects of the presentdisclosure. As shown in FIG. 5 , V2X system 500 includes a transmitterUE 504 transmits data to an RSU 510 and a receiving UE 502 via sidelinktransmissions 512. Additionally, or alternatively, the RSU 510 maytransmit data to the transmitter UE 504 via a sidelink transmission 512.The RSU 510 may forward data received from the transmitter UE 504 to acellular network (e.g., gNB) 508 via an UL transmission 514. The gNB 508may transmit the data received from the RSU 510 to other UEs 506 via aDL transmission 516. The RSU 510 may be incorporated with trafficinfrastructure (e.g., traffic light, light pole, etc.) For example, asshown in FIG. 5 , the RSU 510 is a traffic signal positioned at a sideof a road 520. Additionally or alternatively, RSUs 510 may bestand-alone units.

FIG. 6 is a graph illustrating a sidelink (SL) communications scheme, inaccordance with various aspects of the present disclosure. A scheme 600may be employed by UEs such as the UEs 104 in a network such as thenetwork 100. In FIG. 6 , the x-axis represents time and the y-axisrepresents frequency. The CV2X channels may be for 3GPP Release 16 andbeyond.

In the scheme 600, a shared radio frequency band 601 is partitioned intomultiple subchannels or frequency subbands 602 (shown as 602 _(S0), 602_(S1), 602 _(S2)) in frequency and multiple sidelink frames 604 (shownas 604 a, 604 b, 604 c, 604 d) in time for sidelink communications. Thefrequency band 601 may be at any suitable frequencies. The frequencyband 601 may have any suitable bandwidth (BW) and may be partitionedinto any suitable number of frequency subbands 602. The number offrequency subbands 602 can be dependent on the sidelink communicationsBW requirement.

Each sidelink frame 604 includes a sidelink resource 606 in eachfrequency subband 602. A legend 605 indicates the types of sidelinkchannels within a sidelink resource 606. In some instances, a frequencygap or guard band may be specified between adjacent frequency subbands602, for example, to mitigate adjacent band interference. The sidelinkresource 606 may have a substantially similar structure as an NRsidelink resource. For instance, the sidelink resource 606 may include anumber of subcarriers or RBs in frequency and a number of symbols intime. In some instances, the sidelink resource 606 may have a durationbetween about one millisecond (ms) to about 20 ms. Each sidelinkresource 606 may include a PSCCH 610 and a PSSCH 620. The PSCCH 610 andthe PSSCH 620 can be multiplexed in time and/or frequency. The PSCCH 610may be for part one of a control channel (CCH), with the second partarriving as a part of the shared channel allocation. In the example ofFIG. 6 , for each sidelink resource 606, the PSCCH 610 is located duringthe beginning symbol(s) of the sidelink resource 606 and occupies aportion of a corresponding frequency subband 602, and the PSSCH 620occupies the remaining time-frequency resources in the sidelink resource606. In some instances, a sidelink resource 606 may also include aphysical sidelink feedback channel (PSFCH), for example, located duringthe ending symbol(s) of the sidelink resource 606. In general, a PSCCH610, a PSSCH 620, and/or a PSFCH may be multiplexed within a sidelinkresource 606.

The PSCCH 610 may carry SCI 660 and/or sidelink data. The sidelink datacan be of various forms and types depending on the sidelink application.For instance, when the sidelink application is a V2X application, thesidelink data may carry V2X data (e.g., vehicle location information,traveling speed and/or direction, vehicle sensing measurements, etc.).Alternatively, when the sidelink application is an IIoT application, thesidelink data may carry IIoT data (e.g., sensor measurements, devicemeasurements, temperature readings, etc.). The PSFCH can be used forcarrying feedback information, for example, HARQ ACK/NACK for sidelinkdata received in an earlier sidelink resource 606.

In an NR sidelink frame structure, the sidelink frames 604 in a resourcepool 608 may be contiguous in time. A sidelink UE (e.g., the UEs 104)may include, in SCI 660, a reservation for a sidelink resource 606 in alater sidelink frame 604. Thus, another sidelink UE (e.g., a UE in thesame NR-U sidelink system) may perform SCI sensing in the resource pool608 to determine whether a sidelink resource 606 is available oroccupied. For instance, if the sidelink UE detected SCI indicating areservation for a sidelink resource 606, the sidelink UE may refrainfrom transmitting in the reserved sidelink resource 606. If the sidelinkUE determines that there is no reservation detected for a sidelinkresource 606, the sidelink UE may transmit in the sidelink resource 606.As such, SCI sensing can assist a UE in identifying a target frequencysubband 602 to reserve for sidelink communications and to avoidintra-system collision with another sidelink UE in the NR sidelinksystem. In some aspects, the UE may be configured with a sensing windowfor SCI sensing or monitoring to reduce intra-system collision.

In some aspects, the sidelink UE may be configured with a frequencyhopping pattern. In this regard, the sidelink UE may hop from onefrequency subband 602 in one sidelink frame 604 to another frequencysubband 602 in another sidelink frame 604. In the illustrated example ofFIG. 6 , during the sidelink frame 604 a, the sidelink UE transmits SCI660 in the sidelink resource 606 located in the frequency subband 602_(S2) to reserve a sidelink resource 606 in a next sidelink frame 604 blocated at the frequency subband 602 _(S1). Similarly, during thesidelink frame 604 b, the sidelink UE transmits SCI 662 in the sidelinkresource 606 located in the frequency subband 602 _(S1) to reserve asidelink resource 606 in a next sidelink frame 604 c located at thefrequency subband 602S1. During the sidelink frame 604 c, the sidelinkUE transmits SCI 664 in the sidelink resource 606 located in thefrequency subband 602 _(S1) to reserve a sidelink resource 606 in a nextsidelink frame 604 d located at the frequency subband 602 _(S0). Duringthe sidelink frame 604 d, the sidelink UE transmits SCI 668 in thesidelink resource 606 located in the frequency subband 602 _(S0). TheSCI 668 may reserve a sidelink resource 606 in a later sidelink frame604.

The SCI can also indicate scheduling information and/or a destinationidentifier (ID) identifying a target receiving sidelink UE for the nextsidelink resource 606. Thus, a sidelink UE may monitor SCI transmittedby other sidelink UEs. Upon detecting SCI in a sidelink resource 606,the sidelink UE may determine whether the sidelink UE is the targetreceiver based on the destination ID. If the sidelink UE is the targetreceiver, the sidelink UE may proceed to receive and decode the sidelinkdata indicated by the SCI. In some aspects, multiple sidelink UEs maysimultaneously communicate sidelink data in a sidelink frame 604 indifferent frequency subband (e.g., via frequency division multiplexing(FDM)). For instance, in the sidelink frame 604 b, one pair of sidelinkUEs may communicate sidelink data using a sidelink resource 606 in thefrequency subband 602 _(S2) while another pair of sidelink UEs maycommunicate sidelink data using a sidelink resource 606 in the frequencysubband 602 si.

In some aspects, the scheme 600 is used for synchronous sidelinkcommunications. That is, the sidelink UEs may be synchronized in timeand are aligned in terms of symbol boundary, sidelink resource boundary(e.g., the starting time of sidelink frames 604). The sidelink UEs mayperform synchronization in a variety of forms, for example, based onsidelink SSBs received from a sidelink UE and/or NR-U SSBs received froma BS (e.g., the BSs 105 and/or 205) while in-coverage of the BS. In someaspects, the sidelink UE may be preconfigured with the resource pool 608in the frequency band 601, for example, while in coverage of a servingBS. The resource pool 608 may include a plurality of sidelink resources606. The BS can configure the sidelink UE with a resource poolconfiguration indicating resources in the frequency band 601 and/or thesubbands 602 and/or timing information associated with the sidelinkframes 604. In some aspects, the scheme 600 includes mode-2 radioresource allocation (RRA) (e.g., supporting autonomous RRA that can beused for out-of-coverage sidelink UEs or partial-coverage sidelink UEs).

As described above, a first user (e.g., user-A) may transmit messages toa second user (e.g., user-B) for high-data rate vehicular applications,such as a raw sensing data exchange or collaborative virtual realitygaming. In some examples, user-A may experience reduced communicationcapability based on transmitting the messages to user-B. For example,user-A may experience intermittent outages. The reduced communicationcapability may be due to vehicular mobility and/or blockage of thecommunication path between vehicles. In order to enable robust andefficient communication, user-A performs additional training forbeamforming and communication channel sensing, which creates additionaloverhead and decreases the communication data rate.

According to aspects of the present disclosure, user-A may performhigh-data rate communications with user-B's vehicular applications in arobust and efficient manner, while reducing the need for additionaltraining overhead. User-A may adaptively select transmit parametersusing joint communication-radar (JCR) side information. Additionally,user-A may obtain the JCR side information by associating andcorrelating its radar side information with vehicle-to-everything (V2X)messages received from user-B.

In some examples, user-A may receive V2X messages from user-B. The V2Xmessages received from user-B may include a personal safety message(PSM) and a basic safety message (BSM) to potentially enhance safety aswell as traffic efficiency. User-A and user-B can be vehicles orvulnerable road users (VRUs). Pedestrians, bicyclists, and roadconstruction crews are examples of VRUs. Devices at user-A and user-Bmay include cell phones, vehicle/bike mounted hardware, and constructionequipment, for example.

FIG. 7 is a block diagram illustrating vehicle-to-everything (V2X)communication, in accordance with various aspects of the presentdisclosure. In FIG. 7 , user-B transmits a V2X message 702 to user-A. Inthe example of FIG. 7 , the V2X message 702 is a binary message with thecontent 10100. As shown in the example of FIG. 7 , user-A is travellingat 12 m/s, user-B is travelling at 20 m/s, and a third vehicle 704 istravelling at 15 m/s. The third vehicle 704 may not support V2Xcommunication. In the example of FIG. 7 , one or more events may affecta communication link between user-A and user-B. As an example, the thirdvehicle 704 may possibly change lanes and position itself between user-Aand user-B, which would block the communication link between user-A anduser-B. As another example, user-B may accelerate, which may negativelyaffect the communication link between user-A and user-B.

The V2X message 702 may contain one or more data fields, such as, threedimensional (3D) location information, direction heading, acceleration,velocity, personal crossing in progress, path history, path prediction,user type, size, behavior, personal assistive device information, publicsafety and road worker activity, future intentions, and signal-to-noiseratio at the communication receiver of user-B. The one or more datafields of the V2X message 702 may be updated at a limited rate due tothe limited transmission rate of the V2X message 702. The 3D locationinformation may be provided by a global positioning system (GPS). Insome examples, the 3D location information may not be accurate, forexample, due to the movement of user-B. The future intentions data fieldmay indicate a personal crossing request or lane change request, forexample.

In the example of FIG. 7 , a communication receiver at user-A receivesV2X messages 702 from user-B to announce the presence of user-B andprovide details about the future intentions of user-B. As noted above,the third vehicle 704 may possibly initiate a lane change maneuver,disrupting a communication link between user-A and user-B. Thedisruption to the communication link may limit user-A's knowledge ofpresent and future one-way bi-static channel state information (CSI). Aline-of-sight (LoS) link may be an example of a communication link.

In some examples, user-A may have radar detection and estimationcapabilities. FIG. 8 is a block diagram illustrating radar sensing, inaccordance with various aspects of the present disclosure. In theexample of FIG. 8 , user-A employs radar to sense the environment toenable safety and comfort features, such as collision avoidance andadaptive cruise control. The radar periodically transmits a radar signal802 to sense the environment. The sensing occurs with a high updaterate. The radar signal 802 is reflected by surrounding objects (e.g.,the third vehicle 704 and user-B) and the echoes are received at theradar receiver in a full-duplex configuration. The received signal isthen processed to estimate the two-way monostatic channel parameters atuser-A. In FIG. 8 , user-A senses user-B and the third vehicle 704 withthe radar signals 802.

Radar may estimate various target parameters, such as range profile,velocity profile, angular profile, radar signature, target tracking,target behavior and path prediction. The velocity profile may beestimated for non-rigid objects, such as bicycles and pedestrians. Thevelocity profile may also provide micro-Doppler characteristics. Theradar signature may enable target classification, and estimate a targetshape and size.

In FIG. 8 , a radar receiver at user-A transmits a radar signal 802 andreceives echoes of the radar signal 802 from surrounding vehicles (e.g.,the third vehicle 704 and user-B) to estimate the two-way monostaticchannel parameters at a high update rate. The radar receiver processesthe estimated channel to characterize the state, tracking information,and prediction behavior of the relevant targets. The position andvelocity estimation accuracies are high due to the wide availablebandwidths, use of antenna arrays, and long coherent processinginterval. However, radar suffers from poor data association and haslimited sensing capability when there is a blockage.

As described, user-A transmits communication messages to user-B forhigh-data rate vehicular applications, such as raw sensing data exchangeor collaborative virtual reality gaming. User-A may transmit its signalat a millimeter wave (mmWave) band (for example, 73 GHz) with a highbandwidth (for example, 2 GHz) to achieve a high-data rate (a few Gb/s).However, user-A's communication capability may be reduced due tovehicular mobility, communication link blockage, and accelerations fromsurrounding vehicles, such as user-B. To enable robust and efficientcommunication, user-A performs additional training for beamforming andcommunication channel sensing. This training and sensing, however, addsadditional overhead and decreases the communication data rate.

Aspects of the present disclosure are directed to a robust, efficient,and high-data rate solution for communications from user-A to user-B'sin vehicular applications. Aspects of the present disclosure may alsoreduce the need for additional training overhead. According to aspectsof the present disclosure, user-A adaptively selects transmit parametersusing joint communication-radar (JCR) side information. User-A mayobtain this JCR side information by associating and correlating itsradar side information with the V2X messages received from user-B.

FIG. 9 is a block diagram illustrating V2X communication, in accordancewith various aspects of the present disclosure. In the example of FIG. 9, a communication transmitter at user-A sends a communication message902 to user-B for high-data rate applications, such as vehicularapplications. As described, the third vehicle 704 may not support V2Xcommunication. Additionally, in the example of FIG. 9 , one or moreevents may affect a communication link between user-A and user-B. As anexample, the third vehicle 704 may possibly initiate a lane changemaneuver and position itself between user-A and user-B, therebydisrupting the line-of-sight (LoS) link (e.g., communication link)between user-A and user-B. As another example, user-B may also begin toaccelerate away from user-A, which may cause a poor communication linkwith user-B. Aspects of the present disclosure address these potentialcommunication issues, in addition to other types of communicationissues.

FIG. 10 is a call flow diagram illustrating communication transmitparameter selection, in accordance with various aspects of the presentdisclosure. At time t1, user-A receives V2X messages from user-B toannounce the presence of user-B, as well as future intentions of user-B.The V2X messages may be periodically received by user-A. The messagesare received at a low update rate. At time t2, user-A periodicallytransmits a radar signal to sense the environment for safety and comfortfeatures. The radar signals may be transmitted at a high update rate. Attime t3, user-A processes the radar echoes to estimate channel sensingparameters, to perform target tracking, and to predict a path/behaviorof detected objects.

At time t4, user-A estimates JCR side information by finding anassociation and correlation between the radar information and thereceived V2X messages. Based on the JCR side information, at time t5user-A characterizes and predicts the communication state. Thecommunication state may include, for example, a type of communicationlink, channel delay, Doppler information, and angular spread estimates.At time t6, user-A may optimize and update its communication transmitparameters based on the communication state characterization andprediction. These parameters may include, for example, beamforming andwaveform parameters.

Joint communication-radar (JCR) side information will now be discussedin more detail. JCR information may also be referred to as RADCOM orjoint radar and communication, or collocated and cooperative radar andcommunication information. There are similarities and dissimilaritiesbetween the radar side information and the received V2X messages. Theradar side information may be based on the two-way monostatic radarchannel state. The V2X messages may provide limited information on itspresent and future one-way bi-static channel state and user behavior.JCR side information may be obtained by determining an association andcorrelation between the parameters estimated by radar and theinformation communicated by user-B in V2X messages.

JCR side-information may contain estimated parameters for thesurrounding objects, including user-B, such as location and headingestimates, velocity and acceleration profile estimates, and objectsignature, such as object type (e.g., pedestrian, vehicle, bicycle),orientation, size and shape, tracking, and predicted behavior. The JCRinformation may also contain estimated parameters for presence ofblockage between the object and user-A, feasibility of a line-of-sight(LoS) link in the near future, and possible scattering clusters thatmight be used in non-LoS scenarios for reflecting the signals to user-B.The JCR side-information may also provide a confidence measure for thepreviously mentioned estimated parameters.

As noted above, V2X messages received from user-B at user-A containlimited information on the present and future one-way bi-static channelstate. Radar sensing enables better estimation of user-B's location andmotion profile. Additionally, radar sensing increases an update rate ofthe estimates based on the radar's high update rate. Radar sensing mayalso estimate the radar parameters for the third vehicle 704 (FIG. 8 )with no V2X support.

According to aspects of the present disclosure, where there is noblockage between user-A and user-B, user-A receives V2X communicationside information from user-B with location estimates and futureintentions of user-B. User-A transmits the radar signal and receivesechoes from surrounding objects, including a LoS reflection from user-B.The radar may perform detection, estimation, tracking, and behaviorprediction of surrounding objects.

Based on the similar location parameters obtained from V2X messages andradar side information, user-A associates the relevant target echodetected in the radar channel with user-B. Additionally, an estimatedradar signature can be correlated with the typical radar signature ofuser-B, based on the information received from V2X messages, to increasethe confidence level in the LoS association to user-B. For example,micro-Doppler characteristics may help identify users such as a bicycleor pedestrian, which may be confirmed from the user type data field inthe V2X messages.

In this example, user-A characterizes the communication link betweenuser-A and user-B as line-of-sight (LoS). User-A also predicts thefeasibility of a communication LoS link based on JCR side information.If the prediction indicates a LoS link is feasible, the transmitter atuser-A selects a narrow beam width pointing towards user-B. Thetransmitter may also be configured with a smaller cyclic prefix, and/ora higher modulation and coding scheme (MCS) level to increase thecommunication data rate.

If the prediction indicates the LoS link is not feasible, but there is anon-LoS (NLoS) path, user-A finds relevant scatters to bounce-off thesignals to user-B among all the targets estimated by the radar. Acommunication transmitter of user-A may adapt its beamformingparameters, such as beam width and shape depending on the current LoSand predicted NLoS communication channel state. The transmitter may alsobe configured with an increased cyclic prefix length, decreased MCSlevel, and increased transmit power to enable robust and efficientcommunication for an NLoS path.

More detail will now be presented for when a blockage occurs betweenuser-A and user-B. In this example, user-A receives V2X communicationside information with location information and future intentions ofuser-B. The radar may sense its channel but user-A is unable toassociate any of its detected LoS target echoes with user-B based on thejoint communication-radar (JCR) side information. The channel may beindicated as NLoS when there is no association between radar targetlocations and the location of user-B. In this case, the NLoS scenarioobserved by the radar may be used to provide a coarse estimate ofsuitable transmit power, beamforming shape and gain, beam width, cyclicprefix length, and MCS level to enable robust and efficient NLoScommunication with reduced outage.

Based on possible correlations between radar data and received V2Xmessages, user-A uses the radar side information to locate candidatetargets of interest that could be used to reflect the signals from thecommunication transmitter at user-A to the communication receiver atuser-B. These possible targets of interest for communication purposesmay be obtained by finding the scatters that have a high bi-staticreflection coefficient and small path loss. The candidate targets mayalso be selected based on current location estimates. For example,detected radar targets that fall in-between the locations of user-A anduser-B may be chosen. User-B's current location and predicted behaviormay be communicated via V2X messages.

In some aspects of the present disclosure, the target list may be prunedand optimized based on the user type, current activity, and futureintentions of user-B, received from V2X messages. As an example, a flatsurface such as the side of a car may be used to reflect signals touser-B with a straight path, whereas a circular surface such as thecorner of the car may be used to reflect the signal when user-B ismaking a turn.

The reflection target may be selected based on tracking information andpredicted behavior of both the users. For example, the location, speedand heading information, and predicted behavior information for user-Bprovided by V2X messages along with the radar targets tracking andpredicted behavior estimation may be considered. The detected radartargets with a predicted path falling in-between the two users for along duration may be preferred. Those radar targets that are predictedto take a turn (when both the users are travelling straight) may not beconsidered.

Other factors for pruning include the amplitude of the target scatteringclusters. For example, the dominant scatters/scattering clusters in themonostatic radar channel may be selected for reflecting signals to thecommunication receiver. This will enable exploiting some of thesimilarities between the monostatic radar reflectivity and bi-staticcommunication reflectivity of a scatter. For example, a metallic surfacehas high reflectivity and a pedestrian has low reflectivity in bothmonostatic radar and bi-static communication channels.

Other factors for pruning include the range, Doppler characteristics,and angular spread associated with the targets. For example, largesurfaces will generally have high range/Doppler/angular spread and mayprovide robustness for NLoS communication.

Additional factors for pruning include the bi-static radar cross section(RCS). For example, if there is a large flat surface (such as the sideof a car or truck) detected by the radar between the two users withoutblocking the path, then the large flat surface may be used forreflecting the signal to the communication receiver mounted on user-B,which is travelling straight (as communicated by V2X messages). Thelarge flat surface has a high bi-static RCS.

According to aspects of the present disclosure, after selecting areflecting target, the communication transmitter of user-A adapts itsbeamforming parameters, such as beam width and shape depending on thepredicted NLoS communication channel state including the selectedtargets for reflecting the signal. The transmitter may also beconfigured to increases the cyclic prefix length, decrease the MCSlevel, and/or increase the transmit power to enable robust and efficientcommunication.

If the targets are widely separated and the communication receiver isfar away, then a multi-beam may be preferred. If the targets are closelyseparated and the communication receiver is near, then a single broadbeam may be used. If radar observes a dense NLoS scenario, thecommunication transmitter may increase the cyclic prefix length,decrease the MCS level, and/or increase the transmit power for enhancedcommunication.

In further aspects of the present disclosure, user-A estimates theDoppler-shift profile of a LoS communication channel. In these aspects,user-A receives V2X communication side information with locationinformation and future intentions of user-B. User-A transmits its radarsignal and receives echoes from surrounding objects, including a LoSreflection from user-B. The radar also performs detection, estimation,tracking, and behavior prediction of surrounding objects. Similar toother aspects of the disclosure, user-A associates the relevant targetdetected in the radar channel with user-B and thus characterizes andpredicts the communication link between user-A and user-B asline-of-sight (LoS). User-A may also estimate and predict aDoppler-shift profile of the LoS communication channel based on radardata and V2X messages.

If the radar estimates a high Doppler shift and high Doppler spread forthe target corresponding to communication with user-B, the communicationtransmitter may reduce its frame length, use a moderate beam width(meaning neither too narrow nor too wide), and change its waveformparameters. For example, the transmitter may be configured to increase asubcarrier spacing in orthogonal frequency division multiplexing (OFDM),or use a different waveform that is more robust. If the radar estimateslow Doppler shift and low Doppler spread for the target corresponding tocommunication with user-B, the communication transmitter may increaseits frame length, use a narrow beam, and change its waveform parameterssuch as reducing subcarrier spacing in OFDM.

Using radar as a coarse estimate for selecting suitable communicationtransmit parameters may reduce communication training overhead, wherethe communication training is directed to finding the best beam andwaveform parameters. After the coarse estimate is received from radar,communication can further optimize the best beamforming shape and gainif needed. Therefore, the communication data rate improves and outagesmay be reduced.

As indicated above, FIGS. 7-10 are provided as examples. Other examplesmay differ from what is described with respect to FIGS. 7-10 .

FIG. 11 is a flow diagram illustrating an example process 1100performed, for example, by a user equipment, in accordance with variousaspects of the present disclosure. The example process 1100 is anexample of a vehicle-to-everything (V2X) communication transmitparameter selection using joint communication-radar side information.The operations of the process 1100 may be implemented by a UE 104.

At block 1102, the user equipment (UE) receives a vehicle-to-everything(V2X) message from a second UE. For example, the UE (e.g., using theantenna 352, receive processor 356, receiver 354, controller/processor359, and/or memory 360) may receive the message. The message mayannounce the presence of the second UE, as well as future intentions ofthe second UE. The message may be received at a low update rate.

At block 1104, the user equipment (UE) periodically transmits andreceives a radar signal to sense an environment of the first UE. Forexample, the UE (e.g., using the antenna 352, receive processor 356,transmit processor 368, Rx/Tx 354, controller/processor 359, and/ormemory 360) may transmit and receive the radar signal. The radar signalsmay be transmitted and received at a high update rate.

At block 1106, the user equipment (UE) estimates joint communication andradar side information based on the V2X message and the radar signal.For example, the UE (e.g., using memory 360, and/or controller/processor359) may estimate the joint communication and radar (JCR) sideinformation. JCR information may also be referred to as RADCOM or jointradar and communication, or collocated and cooperative radar andcommunication information. At block 1108, the user equipment (UE)predicts a communication state between the first UE and the second UEbased on the joint communication and radar side information. Forexample, the UE (e.g., using memory 360, and/or controller/processor359) may predict the communication state. The communication state mayinclude a line of sight path or a non-line of sight path between thefirst UE and the second UE.

At block 1110, the user equipment (UE) updates communication transmitparameters based on the communication state. For example, the UE (e.g.,using memory 360, and/or controller/processor 359) may update thecommunication transmit parameters. The communication transmit parametersmay configure a beam pointing towards the second UE, and may configure adecreased cyclic prefix (CP) length, and/or an increased modulation andcoding scheme (MCS) when the path is line of sight. The communicationtransmit parameters may configure a beam pointing towards a target forreflecting towards the second UE, and may configure an increased cyclicprefix (CP) length, and/or an decreased modulation and coding scheme(MCS) when the path is non-line of sight.

Implementation examples are described in the following numbered clauses.

-   -   1. A method of wireless communication by a first user equipment        (UE), comprising:        -   receiving a vehicle-to-everything (V2X) message from a            second UE;        -   periodically transmitting and receiving a radar signal to            sense an environment of the first UE;        -   estimating joint communication and radar side information            based on the V2X message and the radar signal;        -   predicting a communication state between the first UE and            the second UE based on the joint communication and radar            side information; and        -   updating communication transmit parameters based on the            communication state.    -   2. The method of clause 1, in which the communication state        includes a line of sight path between the first UE and the        second UE, and the communication transmit parameters configure a        beam pointing towards the second UE.    -   3. The method of clause 1 or 2, in which the communication        transmit parameters configure at least one of a decreased cyclic        prefix (CP) length, or an increased modulation and coding scheme        (MCS).    -   4. The method of any of the preceding clauses, in which the beam        has a narrow beam width.    -   5. The method of any of the preceding clauses, further        comprising:        -   estimating a Doppler shift associated with the line of sight            path based on the V2X message and the radar signal; and        -   adjusting the communication transmit parameters based on the            Doppler shift.    -   6. The method of clause 1, in which the communication state        includes a non-line of sight path between the first UE and the        second UE, and the communication transmit parameters configure a        beam pointing towards a target for reflecting to the second UE.    -   7. The method of any of the clauses 1 or 6, in which the        communication transmit parameters configure at least one of an        increased transmission power, an increased cyclic prefix (CP)        length, or a decreased modulation and coding scheme (MCS).    -   8. The method of any of the clauses 1, 6, or 7, in which the        beam has a wide beam width.    -   9. The method of any of the clauses 1, 6, 7, or 8, further        comprising determining the target from a plurality of candidate        targets based on at least one of: a current location of the        second UE, a predicted behavior of the second UE, a current        location of the first UE, a path loss between the first UE and        each of the plurality of candidate targets, a path loss between        the second UE and each of the plurality of candidate targets, or        a reflection coefficient of each of the plurality of candidate        targets.    -   10. The method of any of the clauses 1, 6, 7, 8, or 9, further        comprising selecting the target from a plurality of candidate        targets based on at least one of: a type of the second UE, an        activity of the second UE, an activity of the first UE, a type        of the first UE, a range of each of the plurality of candidate        targets, a Doppler shift associated with each of the plurality        of candidate targets, or an angular spread associated with each        of the plurality of candidate targets.    -   11. An apparatus for wireless communication by a first user        equipment (UE), comprising:        -   a memory; and        -   at least one processor coupled to the memory, the at least            one processor configured:            -   to receive a vehicle-to-everything (V2X) message from a                second UE;            -   to periodically transmit and receive a radar signal to                sense an environment of the first UE;            -   to estimate joint communication and radar side                information based on the V2X message and the radar                signal;            -   to predict a communication state between the first UE                and the second UE based on the joint communication and                radar side information; and            -   to update communication transmit parameters based on the                communication state.    -   12. The apparatus of clause 11, in which the communication state        includes a line of sight path between the first UE and the        second UE, and the communication transmit parameters configure a        beam pointing towards the second UE.    -   13. The apparatus of clause 11 or 12, in which the communication        transmit parameters configure at least one of a decreased cyclic        prefix (CP) length, or an increased modulation and coding scheme        (MCS).    -   14. The apparatus of any of the clauses 11-13, in which the beam        has a narrow beam width.    -   15. The apparatus of any of the clauses 11-14, in which the at        least one processor is further configured:        -   to estimate a Doppler shift associated with the line of            sight path based on the V2X message and the radar signal;            and        -   to adjust the communication transmit parameters based on the            Doppler shift.    -   16. The apparatus of any of the clause 11, in which the        communication state includes a non-line of sight path between        the first UE and the second UE, and the communication transmit        parameters configure a beam pointing towards a target for        reflecting to the second UE.    -   17. The apparatus of any of the clauses 11 or 16, in which the        communication transmit parameters configure at least one of an        increased transmission power, an increased cyclic prefix (CP)        length, or a decreased modulation and coding scheme (MCS).    -   18. The apparatus of any of the clauses 11 or 16-17, in which        the beam has a wide beam width.    -   19. The apparatus of any of the clauses 11 or 16-18, in which        the at least one processor is further configured to determine        the target from a plurality of candidate targets based on at        least one of: a current location of the second UE, a predicted        behavior of the second UE, a current location of the first UE, a        path loss between the first UE and each of the plurality of        candidate targets, a path loss between the second UE and each of        the plurality of candidate targets, or a reflection coefficient        of each of the plurality of candidate targets.    -   20. The apparatus of any of the clauses 11 or 16-19, in which        the at least one processor is further configured to select the        target from a plurality of candidate targets based on at least        one of: a type of the second UE, an activity of the second UE,        an activity of the first UE, a type of the first UE, a range of        each of the plurality of candidate targets, a Doppler shift        associated with each of the plurality of candidate targets, or        an angular spread associated with each of the plurality of        candidate targets.    -   21. An apparatus for wireless communication by a first user        equipment (UE), comprising:        -   means for receiving a vehicle-to-everything (V2X) message            from a second UE;        -   means for periodically transmitting and receiving a radar            signal to sense an environment of the first UE;        -   means for estimating joint communication and radar side            information based on the V2X message and the radar signal;        -   means for predicting a communication state between the first            UE and the second UE based on the joint communication and            radar side information; and        -   means for updating communication transmit parameters based            on the communication state.    -   22. The apparatus of clause 21, in which the communication state        includes a line of sight path between the first UE and the        second UE, and the communication transmit parameters configure a        beam pointing towards the second UE.    -   23. The apparatus of clause 21 or 22, in which the communication        transmit parameters configure at least one of a decreased cyclic        prefix (CP) length, or an increased modulation and coding scheme        (MCS).    -   24. The apparatus of any of the clauses 21-23, in which the beam        has a narrow beam width.    -   25. The apparatus of any of the clauses 21-24, further        comprising:        -   means for estimating a Doppler shift associated with the            line of sight path based on the V2X message and the radar            signal; and        -   means for adjusting the communication transmit parameters            based on the Doppler shift.    -   26. The apparatus of clause 21, in which the communication state        includes a non-line of sight path between the first UE and the        second UE, and the communication transmit parameters configure a        beam pointing towards a target for reflecting to the second UE.    -   27. The apparatus of any of the clauses 21 or 26, in which the        communication transmit parameters configure at least one of an        increased transmission power, an increased cyclic prefix (CP)        length, or a decreased modulation and coding scheme (MCS).    -   28. The apparatus of any of the clauses 21 or 26-27, in which        the beam has a wide beam width.    -   29. The apparatus of any of the clauses 21 or 26-28, further        comprising means for determining the target from a plurality of        candidate targets based on at least one of: a current location        of the second UE, a predicted behavior of the second UE, a        current location of the first UE, a path loss between the first        UE and each of the plurality of candidate targets, a path loss        between the second UE and each of the plurality of candidate        targets, or a reflection coefficient of each of the plurality of        candidate targets.    -   30. The apparatus of any of the clauses 21 or 26-29, further        comprising means for selecting the target from a plurality of        candidate targets based on at least one of: a type of the second        UE, an activity of the second UE, an activity of the first UE, a        type of the first UE, a range of each of the plurality of        candidate targets, a Doppler shift associated with each of the        plurality of candidate targets, or an angular spread associated        with each of the plurality of candidate targets.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used, the term “component” is intended to be broadly construed ashardware, firmware, and/or a combination of hardware and software. Asused, a processor is implemented in hardware, firmware, and/or acombination of hardware and software.

Some aspects are described in connection with thresholds. As used,satisfying a threshold may, depending on the context, refer to a valuebeing greater than the threshold, greater than or equal to thethreshold, less than the threshold, less than or equal to the threshold,equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described may beimplemented in different forms of hardware, firmware, and/or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the aspects. Thus, the operation and behavior of thesystems and/or methods were described without reference to specificsoftware code—it being understood that software and hardware can bedesigned to implement the systems and/or methods based, at least inpart, on the description.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used should be construed as critical oressential unless explicitly described as such. Also, as used, thearticles “a” and “an” are intended to include one or more items, and maybe used interchangeably with “one or more.” Furthermore, as used, theterms “set” and “group” are intended to include one or more items (e.g.,related items, unrelated items, a combination of related and unrelateditems, and/or the like), and may be used interchangeably with “one ormore.” Where only one item is intended, the phrase “only one” or similarlanguage is used. Also, as used, the terms “has,” “have,” “having,”and/or the like are intended to be open-ended terms. Further, the phrase“based on” is intended to mean “based, at least in part, on” unlessexplicitly stated otherwise.

What is claimed is:
 1. A method of wireless communication by a first user equipment (UE), comprising: receiving a vehicle-to-everything (V2X) message from a second UE; periodically transmitting and receiving a radar signal to sense an environment of the first UE; estimating joint communication and radar side information based on the V2X message and the radar signal; predicting a communication state between the first UE and the second UE based on the joint communication and radar side information, the communication state including a non-line of sight path between the first UE and the second UE; and updating communication transmit parameters to configure a beam pointing towards a target of a plurality of targets for reflecting to the second UE based on the communication state, the communication transmit parameters configuring an increased transmission power and an increased cyclic prefix (CP) length.
 2. The method of claim 1, in which the communication transmit parameters configure a decreased modulation and coding scheme (MCS).
 3. The method of claim 1, further comprising determining the target from the plurality of candidate targets based on at least one of: a current location of the second UE, a predicted behavior of the second UE, a current location of the first UE, a path loss between the first UE and each of the plurality of candidate targets, a path loss between the second UE and each of the plurality of candidate targets, or a reflection coefficient of each of the plurality of candidate targets.
 4. The method of claim 1, further comprising selecting the target from the plurality of candidate targets based on at least one of: a type of the second UE, an activity of the second UE, an activity of the first UE, a type of the first UE, a range of each of the plurality of candidate targets, a Doppler shift associated with each of the plurality of candidate targets, or an angular spread associated with each of the plurality of candidate targets.
 5. An apparatus for wireless communication by a first user equipment (UE), comprising: a memory; and at least one processor coupled to the memory, the at least one processor configured: to receive a vehicle-to-everything (V2X) message from a second UE; to periodically transmit and receive a radar signal to sense an environment of the first UE; to estimate joint communication and radar side information based on the V2X message and the radar signal; to predict a communication state between the first UE and the second UE based on the joint communication and radar side information, the communication state including a non-line of sight path between the first UE and the second UE; and to update communication transmit parameters to configure a beam pointing towards a target of a plurality of targets for reflecting to the second UE based on the communication state, the communication transmit parameters configuring an increased transmission power and an increased cyclic prefix (CP) length.
 6. The apparatus of claim 5, in which the communication transmit parameters configure a decreased modulation and coding scheme (MCS).
 7. The apparatus of claim 5, in which the at least one processor is further configured to determine the target from the plurality of candidate targets based on at least one of: a current location of the second UE, a predicted behavior of the second UE, a current location of the first UE, a path loss between the first UE and each of the plurality of candidate targets, a path loss between the second UE and each of the plurality of candidate targets, or a reflection coefficient of each of the plurality of candidate targets.
 8. The apparatus of claim 5, in which the at least one processor is further configured to select the target from the plurality of candidate targets based on at least one of: a type of the second UE, an activity of the second UE, an activity of the first UE, a type of the first UE, a range of each of the plurality of candidate targets, a Doppler shift associated with each of the plurality of candidate targets, or an angular spread associated with each of the plurality of candidate targets.
 9. An apparatus for wireless communication by a first user equipment (UE), comprising: means for receiving a vehicle-to-everything (V2X) message from a second UE; means for periodically transmitting and receiving a radar signal to sense an environment of the first UE; means for estimating joint communication and radar side information based on the V2X message and the radar signal; means for predicting a communication state between the first UE and the second UE based on the joint communication and radar side information, the communication state including a non-line of sight path between the first UE and the second UE; and means for updating communication transmit parameters to configure a beam pointing towards a target of a plurality of targets for reflecting to the second UE based on the communication state, the communication transmit parameters configuring an increased transmission power and an increased cyclic prefix (CP) length.
 10. The apparatus of claim 9, in which the communication transmit parameters configure a decreased modulation and coding scheme (MCS).
 11. The apparatus of claim 9, further comprising means for determining the target from the plurality of candidate targets based on at least one of: a current location of the second UE, a predicted behavior of the second UE, a current location of the first UE, a path loss between the first UE and each of the plurality of candidate targets, a path loss between the second UE and each of the plurality of candidate targets, or a reflection coefficient of each of the plurality of candidate targets.
 12. The apparatus of claim 9, further comprising means for selecting the target from the plurality of candidate targets based on at least one of: a type of the second UE, an activity of the second UE, an activity of the first UE, a type of the first UE, a range of each of the plurality of candidate targets, a Doppler shift associated with each of the plurality of candidate targets, or an angular spread associated with each of the plurality of candidate targets. 